It’s not uncommon to come across photographs of smiths standing beside their anvil. However it is unusual to find a painting of the same type. Paintings of a more general nature are the ones which show activities in and around the shop such as “Horse and Buggy Days by Paul Detlefsen.
The portrait which fascinates me most is “Pat Lyon at the Forge” by John Neagle in 1829. There is a fascinating story associated with its commissioning which you can read - America’s First Bank Robbery
http://www.ushistory.org/carpentershall/history/robbery.htm This, in my opinion, is a true portrait.
Jean Leon Gerome Ferris painted a lot of scenes depicting early American History. His painting “The American Cincinnatus” purports to show George Washington forging. I don’t know if this would actually qualify as a portrait as it wasn’t posed but rather imagined.
http://www.fineartprintsondemand.com/artists/ferris/american_cincinnatus.htm George Washington was often compared to the Roman citizen-farmer leader. http://www.mountvernon.org/educational-resources/encyclopedia/cincinnatus
A few years ago a friend of mine asked if he could come to the studio and photograph me at work. He likes to capture a subject then make a painting similar to the image. He has spent a good bit of his retirement time in that activity. When finished, he gave me a print. So now I can join that small group of smiths who can display a painting of them at work on the anvil although this smith will never be considered an American legend.